http2-serverpush.c: example code

docs/examples/Makefile.inc

@@ -32,7 +32,7 @@ check_PROGRAMS = 10-at-a-time anyauthput cookie_interface debug fileupload \
   imap-list imap-lsub imap-fetch imap-store imap-append imap-examine       \
   imap-search imap-create imap-delete imap-copy imap-noop imap-ssl         \
   imap-tls imap-multi url2file sftpget ftpsget postinmemory http2-download \
-  http2-upload
+  http2-upload http2-serverpush
 
 # These examples require external dependencies that may not be commonly
 # available on POSIX systems, so don't bother attempting to compile them here.

docs/examples/http2-serverpush.c

@@ -0,0 +1,313 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at http://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+#include <stdio.h>
+#include <stdlib.h>
+
+/* somewhat unix-specific */
+#include <sys/time.h>
+#include <unistd.h>
+
+/* curl stuff */
+#include <curl/curl.h>
+
+#ifndef CURLPIPE_MULTIPLEX
+#error "too old libcurl, can't do HTTP/2 server push!"
+#endif
+
+static
+void dump(const char *text, unsigned char *ptr, size_t size,
+          char nohex)
+{
+  size_t i;
+  size_t c;
+
+  unsigned int width=0x10;
+
+  if(nohex)
+    /* without the hex output, we can fit more on screen */
+    width = 0x40;
+
+  fprintf(stderr, "%s, %ld bytes (0x%lx)\n",
+          text, (long)size, (long)size);
+
+  for(i=0; i<size; i+= width) {
+
+    fprintf(stderr, "%4.4lx: ", (long)i);
+
+    if(!nohex) {
+      /* hex not disabled, show it */
+      for(c = 0; c < width; c++)
+        if(i+c < size)
+          fprintf(stderr, "%02x ", ptr[i+c]);
+        else
+          fputs("   ", stderr);
+    }
+
+    for(c = 0; (c < width) && (i+c < size); c++) {
+      /* check for 0D0A; if found, skip past and start a new line of output */
+      if (nohex && (i+c+1 < size) && ptr[i+c]==0x0D && ptr[i+c+1]==0x0A) {
+        i+=(c+2-width);
+        break;
+      }
+      fprintf(stderr, "%c",
+              (ptr[i+c]>=0x20) && (ptr[i+c]<0x80)?ptr[i+c]:'.');
+      /* check again for 0D0A, to avoid an extra \n if it's at width */
+      if (nohex && (i+c+2 < size) && ptr[i+c+1]==0x0D && ptr[i+c+2]==0x0A) {
+        i+=(c+3-width);
+        break;
+      }
+    }
+    fputc('\n', stderr); /* newline */
+  }
+}
+
+static
+int my_trace(CURL *handle, curl_infotype type,
+             char *data, size_t size,
+             void *userp)
+{
+  const char *text;
+  (void)handle; /* prevent compiler warning */
+  (void)userp;
+  switch (type) {
+  case CURLINFO_TEXT:
+    fprintf(stderr, "== Info: %s", data);
+  default: /* in case a new one is introduced to shock us */
+    return 0;
+
+  case CURLINFO_HEADER_OUT:
+    text = "=> Send header";
+    break;
+  case CURLINFO_DATA_OUT:
+    text = "=> Send data";
+    break;
+  case CURLINFO_SSL_DATA_OUT:
+    text = "=> Send SSL data";
+    break;
+  case CURLINFO_HEADER_IN:
+    text = "<= Recv header";
+    break;
+  case CURLINFO_DATA_IN:
+    text = "<= Recv data";
+    break;
+  case CURLINFO_SSL_DATA_IN:
+    text = "<= Recv SSL data";
+    break;
+  }
+
+  dump(text, (unsigned char *)data, size, 1);
+  return 0;
+}
+
+static void setup(CURL *hnd)
+{
+  FILE *out = fopen("dl", "wb");
+
+  /* write to this file */
+  curl_easy_setopt(hnd, CURLOPT_WRITEDATA, out);
+
+  /* set the same URL */
+  curl_easy_setopt(hnd, CURLOPT_URL, "https://localhost:8443/index.html");
+
+  /* send it verbose for max debuggaility */
+  curl_easy_setopt(hnd, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(hnd, CURLOPT_DEBUGFUNCTION, my_trace);
+
+  /* HTTP/2 please */
+  curl_easy_setopt(hnd, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_2_0);
+
+  /* we use a self-signed test server, skip verification during debugging */
+  curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYPEER, 0L);
+  curl_easy_setopt(hnd, CURLOPT_SSL_VERIFYHOST, 0L);
+
+#if (CURLPIPE_MULTIPLEX > 0)
+  /* wait for pipe connection to confirm */
+  curl_easy_setopt(hnd, CURLOPT_PIPEWAIT, 1L);
+#endif
+
+}
+
+/* called when there's an incoming push */
+static int server_push_callback(CURL *parent,
+                                CURL *easy,
+                                size_t num_headers,
+                                struct curl_pushheaders *headers,
+                                void *userp)
+{
+  char *headp;
+  size_t i;
+  int *transfers = (int *)userp;
+  char filename[128];
+  FILE *out;
+  static unsigned int count = 0;
+
+  (void)parent; /* we have no use for this */
+
+  sprintf(filename, "push%u", count++);
+
+  /* here's a new stream, save it in a new file for each new push */
+  out = fopen(filename, "wb");
+
+  /* write to this file */
+  curl_easy_setopt(easy, CURLOPT_WRITEDATA, out);
+
+  fprintf(stderr, "**** push callback approves stream %u, got %d headers!\n",
+          count, (int)num_headers);
+
+  for(i=0; i<num_headers; i++) {
+    headp = curl_pushheader_bynum(headers, i);
+    fprintf(stderr, "**** header %u: %s\n", (int)i, headp);
+  }
+
+  headp = curl_pushheader_byname(headers, ":path");
+  if(headp) {
+    fprintf(stderr, "**** The PATH is %s\n", headp /* skip :path + colon */ );
+  }
+
+  (*transfers)++; /* one more */
+  return CURL_PUSH_OK;
+}
+
+
+/*
+ * Download a file over HTTP/2, take care of server push.
+ */
+int main(void)
+{
+  CURL *easy;
+  CURLM *multi_handle;
+  int still_running; /* keep number of running handles */
+  int transfers=1; /* we start with one */
+  struct CURLMsg *m;
+
+  /* init a multi stack */
+  multi_handle = curl_multi_init();
+
+  easy = curl_easy_init();
+
+  /* set options */
+  setup(easy);
+
+  /* add the easy transfer */
+  curl_multi_add_handle(multi_handle, easy);
+
+  curl_multi_setopt(multi_handle, CURLMOPT_PIPELINING, CURLPIPE_MULTIPLEX);
+  curl_multi_setopt(multi_handle, CURLMOPT_PUSHFUNCTION, server_push_callback);
+  curl_multi_setopt(multi_handle, CURLMOPT_PUSHDATA, &transfers);
+
+  /* we start some action by calling perform right away */
+  curl_multi_perform(multi_handle, &still_running);
+
+  do {
+    struct timeval timeout;
+    int rc; /* select() return code */
+    CURLMcode mc; /* curl_multi_fdset() return code */
+
+    fd_set fdread;
+    fd_set fdwrite;
+    fd_set fdexcep;
+    int maxfd = -1;
+
+    long curl_timeo = -1;
+
+    FD_ZERO(&fdread);
+    FD_ZERO(&fdwrite);
+    FD_ZERO(&fdexcep);
+
+    /* set a suitable timeout to play around with */
+    timeout.tv_sec = 1;
+    timeout.tv_usec = 0;
+
+    curl_multi_timeout(multi_handle, &curl_timeo);
+    if(curl_timeo >= 0) {
+      timeout.tv_sec = curl_timeo / 1000;
+      if(timeout.tv_sec > 1)
+        timeout.tv_sec = 1;
+      else
+        timeout.tv_usec = (curl_timeo % 1000) * 1000;
+    }
+
+    /* get file descriptors from the transfers */
+    mc = curl_multi_fdset(multi_handle, &fdread, &fdwrite, &fdexcep, &maxfd);
+
+    if(mc != CURLM_OK) {
+      fprintf(stderr, "curl_multi_fdset() failed, code %d.\n", mc);
+      break;
+    }
+
+    /* On success the value of maxfd is guaranteed to be >= -1. We call
+       select(maxfd + 1, ...); specially in case of (maxfd == -1) there are
+       no fds ready yet so we call select(0, ...) --or Sleep() on Windows--
+       to sleep 100ms, which is the minimum suggested value in the
+       curl_multi_fdset() doc. */
+
+    if(maxfd == -1) {
+#ifdef _WIN32
+      Sleep(100);
+      rc = 0;
+#else
+      /* Portable sleep for platforms other than Windows. */
+      struct timeval wait = { 0, 100 * 1000 }; /* 100ms */
+      rc = select(0, NULL, NULL, NULL, &wait);
+#endif
+    }
+    else {
+      /* Note that on some platforms 'timeout' may be modified by select().
+         If you need access to the original value save a copy beforehand. */
+      rc = select(maxfd+1, &fdread, &fdwrite, &fdexcep, &timeout);
+    }
+
+    switch(rc) {
+    case -1:
+      /* select error */
+      break;
+    case 0:
+    default:
+      /* timeout or readable/writable sockets */
+      curl_multi_perform(multi_handle, &still_running);
+      break;
+    }
+
+    /*
+     * A little caution when doing server push is that libcurl itself has
+     * created and added one or more easy handles but we need to clean them up
+     * when we are done.
+     */
+
+    do {
+      int msgq = 0;;
+      m = curl_multi_info_read(multi_handle, &msgq);
+      if(m && (m->msg == CURLMSG_DONE)) {
+        CURL *e = m->easy_handle;
+        transfers--;
+        curl_multi_remove_handle(multi_handle, e);
+        curl_easy_cleanup(e);
+      }
+    } while(m);
+
+  } while(transfers); /* as long as we have transfers going */
+
+  curl_multi_cleanup(multi_handle);
+
+
+  return 0;
+}